Capacity of yeast-derived products to enhance grapevine immunity and tolerance to combined drought and Botrytis cinerea infection

Viticulture is affected by abiotic and biotic stresses causing yield losses and deterioration of berry quality. Climate change, characterized by alternating periods of increased water supply and drought, poses threats to grapevine production. Among biotic stresses, Botrytis cinerea, the causal agent of grey mold, is a major concern for grapevine cultivation. Romeo®, a yeast-derived product whose active ingredient is cerevisane, is registered against grapevine diseases. While cerevisane has been shown to induce defense responses in grapevine, its efficacy varies depending on the pathogen. To broaden our understanding of the protective potential against grapevine pathogens and the mechanism of action of Saccharomyces cerevisiae-derived products, Romeo® and another yeast-derived product, Cultus LievitoTM, were compared for their capacity to prevent B. cinerea infections. Additionally, the study aimed to investigate whether these products could mitigate the stress determined by different watering conditions and to ascertain possible interactions between biotic and abiotic stress factors. Cultus LievitoTM and Romeo® treatments determined a positive impact on stomatal conductance after water deprivation during the recovery phase. Cultus LievitoTM proved effective in reducing B. cinerea symptoms on grapevine leaves both in regular watered and in drought stressed plants. Cultus LievitoTM treatment induced higher expression of molecular markers related to water stress and pathogenesis such as NCED, STS and PR2. Finally, to investigate the mechanisms underlying the differing efficacy of the two yeast-derived products, we used HPLC to quantify cell wall polysaccharides, separated by molecular mass. The analysis revealed that Cultus LievitoTM contained a higher concentration of oligosaccharides than Romeo®.